Daily Archives: October 4, 2018

Not doing much but I did do something

Yesterday was nothing special, but I did manage to get some things done. I got a massage, finally, and my leg feels great because of it. I also dropped by the local Harbor Freight and got a couple of things I needed to get, including a 12 pack of microfiber wash cloths, the big ones we can use in the shower. The ones I got over the summer are more like face cloths and are just a touch too small for use in the shower, but these are 4″ larger on either dimension so we can stretch them behind our backs and over the shoulders for cleaning where we can’t touch directly. I also picked up some super glue for repairing the Hummels the cat knocked off the shelf, and what is called a flap disk for prepping metal for welding, that fits in the angle grinder. I have a project for my camping friends that requires welding on a steel drum covered in what appears to be powdercoat that will require a lot of mechanical cleaning. This is not a secret project, I’m just repairing the smoker/grill that has a rusted out firebox, so we can have smoked brisket again.

On the Sprint-T front, I have discovered a local source of Subaru JDM (Japanese Domestic Market) take-out engines, cheap. As in complete engines with everything except the ECU for <$1000. I will have to find a flywheel and clutch to use a manual transmission, but really this is a great deal. Now if I only had the $1k and a means of getting it home. And from the same vendor they have the same model engine except for a manual transmission, complete with the Subaru manual transmission all ready to go into another AWD Subaru for <$1600. I contemplated using the OE Subaru to have AWD on the hotrod, but that would require stranding the straight tube front axle and all the money I dropped into prepping it. And TBH while it would probably be faster I'm not copacetic on how legal it would be for Goodguys autocross. I think it would be legal for SCCA Solo racing in A-Mod or E-Mod with ballast, which I would have to use for balance anyway because I can't move the powertrain right to balance the driver. And speaking of balance the front-to-rear balance would be off because the engine would be hanging in front of the front axle, ahead of where I would normally mount the radiator. That's a whole bunch of weight moved way forward of where it would be with the RWD setup, plus a lot of ballast to get to class weight that I could probably set right in front of the rear axle to get the weight back without increasing the polar moment too much but still because I would have to add about 1200 pounds of ballast to make class weight. There is a penalty for both super or turbocharging, and a penalty for AWD, and the weight penalties stack, plus a minimum weight for the class that I will be drastically under anyway. So, all things considered I will probably not install the unit as AWD and probably convert it to RWD by welding the center differential or replacing it with a spool and removing the front drive components. This will probably end up being the cheapest and quickest to build option I have, along with the most reliable and repairable, as all the repair parts are available at my local Subaru dealer.

The fun part comes with buying a standalone ECU to control all the performance functions on the engine. The engine has variable valve timing on both intake and exhaust that can be either bang-bang controlled or PWM controlled to get smooth transition between the available timing settings as RPM increases. Bang-bang control gets the same end performance benefit with a hard transition between modes at a set RPM that can vary depending on if the RPM is increasing or decreasing and is simpler to implement at the controller and for some ECU bang-bang is the only available mode. The downside is the abrupt change in engine power as the valve timing is changed. PWM uses the same engine hardware as bang-bang, but changes the control from either all the way off or all the way on to a little on that gets more on as RPM increases and less on as RPM decreases and gives more power than bang-bang control during the transition. The PWM control starts at a much lower RPM than bang-bang and usually doesn't get fully engaged until a higher RPM than the bang-bang control because the RPM parameters for bang-bang are chosen for the best average power, resulting in too much timing or too little depending on which side of the bang point you're looking at. So PWM gets more power than bang-bang during the transition, which is important for Autocross and SCCA Solo Racing. So I have to look for a controller that has PWM on the output channels that would be used for what Subaru calls AVCS. The fun part is ECU that have PWM valve timing control start at ~$900 and just keep going up from there . The Microsquirt controller is cheap ($314) and has bang-bang control but is a major pain to set up especially for the valve timing control. But for the price I could live with it especially compared to the Holley ECU. About the only thing the Holley could do that the Microsquirt can’t is PWM control over the variable valve timing, things it can do better are pretty much all related to the number of outputs the Holley ECU has that the Microsquirt doesn’t, like individual control of each injector and ignition coil because where the Ms has control of two injector drivers and two ignition drivers for 4 cylinders, meaning they have to be batch fire and waste fire respectively for a 4 cylinder engine, the Holley has 12 of each, meaning there will be at least 16 useless connections on the Holley, but better control over ignition and fuel. Also the Ms controller requires a software upgrade of about $100 on the laptop side and $209 in additional hardware to set the variable valve timing control and a few other variables where the Holley comes with all the software needed to control all the things (and at that price it better come with all the bells and whistles). Either one is going to need harness modifications to connect to all the things that require connections.

And of course whichever one I get will require dynotuning for anything more than just getting it to run, especially the engine speed to change the cam timing, so add a few hundred $ for that for both ECU.

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